The present invention relates to apparatus for spreading a surface material such as asphalt on a path, and in particular relates to a pull spreader that facilitates spreading of surface materials over paths while minimizing disruption of a smooth surface of the path.
Spreaders are well known for applying surface materials such as asphalt or gravel to paths, and a common prior art self-powered asphalt spreader is shown in FIG. 1 at reference numeral 10. It includes a hopper 12 to hold and store surface material 13; a motor 14 to direct rotational force to drive wheels 16; at least one steering wheel 18; and a skreed 20. As is well known the motor 14 directs rotational force to the drive wheels 16 to move the self-powered spreader 10 over a path while the surface material 13 flows typically by gravity or mechanical force from the hopper into and through the skreed 20 to be formed by the skreed 20 into a surface of a path 21. As is well known, the skreed 20 includes controls for setting the surface material 13 such as asphalt at a predetermined width and depth, and with a predetermined surface contour.
Problems associated with such self-powered spreaders are frequently related to the drive wheels 16 spinning while gaining traction and thereby churning up and disrupting a graded smooth surface of the path, especially when the spreader 10 has to climb a sloped path or operate on a wet path. If the wheels disrupt the surface prior to paving by asphalt from the spreader, the spreader has to be removed, the surface smoothed out, and the spreading or paving process started over by the spreader. Often if the drive wheels of such a self-powered spreader spin, the spreader becomes stuck and has to be towed out of the path, a disruptive and time consuming task. An additional problem associated with such self-powered spreaders is that the weight of the surface material in the hopper is transferred to the wheels and they may develop ruts in the surface of the path, requiring that the amount of surface material in the hopper be limited. Consequently such self-powered spreaders that are typically designed for application to narrow paths such as sidewalks are limited in the amount of surface material they may apply before being refilled based upon the traction and weight bearing capacity of the surface of the paths over which they travel. Additionally, known self-powered spreaders having drive wheels under their hoppers are typically limited to operating on smooth surfaces, and therefore the spreaders can only be utilized for applying a final surface coating to a path, such as asphalt. They cannot be utilized on ungraded paths to apply a base layer of gravel or crushed rock, etc., because they need to develop their own traction to move over the path and cannot do so except on relatively smooth surfaces.
Alternative spreaders include pulled spreaders wherein the spreader does not have to generate traction, thus limiting traction disruption of the surface of the path. For example, United Kingdom Patent Application No. GB. 2,226,839A to Byerley shows a spreader having a tapered hopper supported on a frame having non-wheeled runners and a leveling blade to control a depth of the surface material flowing by gravity out of the spreader as the spreader is towed over the path. The Byerley spreader, however, cannot be steered except by the towing vehicle, and therefore that towing vehicle must be on the surface of the path, wherein the traction and weight of the wheels of the towing vehicle risk disruption of the surface of the path. A second alternative, and likely more common spreader is towed by and secured directly under a dump body of a towing and surface material pouring vehicle, so that the towing dump truck may pour the surface material such as asphalt directly into the spreader as the vehicle tows the spreader over the path. Such a spreader is shown for example in U.S. Pat. No. 3,108,517 that issued on Oct. 29, 1963 to Fingland. While placing the spreader directly under the towing dump truck facilitates application of the spreading material, the weight and traction of the wheels of the dump truck risk disruption of the path surface, and the dump truck is typically too large to be able to position the attached spreader on narrower paths, such as sidewalks, or golf cart paths, etc.
Accordingly, there is a need for a spreader that can move and spread a substantial amount and variety of surface materials upon a path without risk of disruption of a smooth surface of the path.
The invention is a pull spreader for spreading a surface material such as asphalt on a path. The pull spreader includes an open-bottomed frame having a first side wall and an opposed second side wall, a front wall extending between the first and second side walls, a screed wall opposed to the front wall and extending between the first and second side walls so that the first and second side walls, front wall and screed wall define a storage chamber for the surface material, wherein the storage chamber has an inlet area defined between top edges of the side walls, front wall and screed wall that is the same as or smaller than a discharge area of the storage chamber defined between bottom edges of the side walls, front wall and screed wall which bottom edges are adjacent a path over which the pull spreader travels. The pull spreader also includes at least one steering wheel secured to a front frame extension extending from the front wall in a direction away from the storage chamber, and the pull spreader also includes a pull coupling secured to the front frame extension so that the pull spreader may be pulled and steered along the path by a cable secured to the pull coupling. The pull spreader also includes a screed discharge secured adjacent the screed wall for forming a smooth layer of the surface material over the path at a predetermined thickness as the pull spreader is pulled along the path.
In a preferred embodiment, the pull coupling includes a power winch having a cable that may be secured to a cable anchor so that the pull spreader pulls itself along the path as the power winch coils the cable around a coil axle of the winch. In a further preferred embodiment, the screed wall may be a V-blade having a junction of two half walls making up the blade being closer to the front wall than the screed discharge, so that the V-blade plows through the surface material stored in the storage chamber and directs the material evenly into the screed discharge as the pull spreader is pulled along the path.
Because the pull spreader can be steered while being pulled, the cable anchor, a pulling winch separate from the pull spreader, or a pulling vehicle does not have to be on the path over which the pull spreader is being pulled, thereby minimizing a risk of disruption of a smooth surface of the path as the pull spreader passes over the path. Because the storage chamber has an inlet area that is the same as or smaller than an outlet area of the storage chamber adjacent the path, the frame and any wheels supporting it do not have to bear the weight of the surface material stored within the storage chamber, thereby further minimizing the risk of disruption of the smooth surface of the path as the pull spreader passes over the path. Because the pull spreader is pulled instead of being moved by a rotational force of wheels attached to the frame, it is not necessary for any such wheels supporting the frame to develop any traction on the surface of the path, further minimizing risk of disruption of the smooth surface of the path. Because the pull spreader is pulled over the path and has an unimpeded discharge outlet for the surface material, the pull spreader may be utilized on an ungraded path surface to apply a base surface material upon the path, and next may be utilized to apply a top surface material over the base surface material. Because the frame does not have to support the weight of the surface material, the storage chamber may store a larger amount of surface material than known self-powered spreaders that employ a hopper to store the surface material.
Accordingly, it is a general object of the present invention to provide a pull spreader that overcomes deficiencies of prior art spreaders of surface material such as asphalt.
It is a more specific object to provide a pull spreader that does not require a traction force to be applied to a surface of a path over which the pull spreader is pulled.
It is yet another object to provide a pull spreader that does not transfer a weight of the surface material stored within the pull spreader to wheels of the pull spreader.
It is a further object to provide a pull spreader that may be utilized to apply a base surface material to an ungraded path and to next apply a top surface material over the base surface material on the path.
It is still another object to provide a spreader having a surface material storage capacity that is not limited by the weight of the surface material.
These and other objects and advantages of this invention will become more readily apparent when the following description is read in conjunction with the accompanying drawings.
FIG. 1 is a perspective view of a prior art selfpowered spreader.
FIG. 2 is a perspective view of a pull spreader constructed in accordance with the present invention.
FIG. 3 is top plan view of the FIG. 2 pull spreader.
FIG. 4 is side plan view of the FIG. 2 pull spreader.
FIG. 5 is a perspective view of an anchor vehicle positioned off of a curved path while the pull spreader is on the curved path.